The Latest Guidance on U.S. Air Travel During the Pandemic

Reminder: A negative pre-flight test isn’t a guarantee you’re not contagious

Pre-flight testing is now require for anyone traveling internationally into the United States. Photo: Ting Shen/Xinhua via Getty

At the end of January, the Centers for Disease Control and Prevention (CDC) updated its guidance for everyone traveling internationally into the United States, including U.S. citizens: The CDC said everyone coming from a foreign country into a U.S. airport needs to get tested no more than three days before flying and has to show their negative result (or acceptable alternate documentation) to the airline before boarding the flight.

Some experts, however, don’t think this guidance will be very effective in stopping the spread of Covid-19, even though that is one of the CDC’s stated goals. In a document detailing the guidance, the CDC it aims to prevent “the further introduction, transmission, and spread of the virus that causes Covid-19 into the United States, including virus variants.” The CDC also generally recommends that all people should not travel right now.

Earlier this month, there was speculation that pre-flight testing would also become a federal requirement for domestic travel, sparked by comments by government officials who said they were discussing the possibility with the CDC. This possibility sparked plenty of criticism: Airlines, concerned that this requirement would further decimate ticket sales, are strongly opposed to this idea, and mandatory testing would certainly complicate people’s travel plans within the United States. Biden’s team, however, has said that this option was not being considered, for now.

But the growing tension over pre-flight testing for both international and domestic flights may be moot. According to Michael Mina, MD, assistant professor of epidemiology at Harvard T.H. Chan School of Public Health, requiring travelers to take a test up to three days before they fly is not very helpful in catching cases.

“It’s just not effective, period,” he told reporters in a Harvard University press call on February 12. The three-day window for pre-flight testing, he explained, would not catch all cases.

“Say you get the test three days before you fly, maybe you get the result the morning that you’re flying,” he said. “[Say] it shows negative. But if you were in your incubation period and the test was still negative three days before you fly, you could be at your absolute peak viral titers while you’re on the flight and you’re still presymptomatic.”

The push for pre-flight testing “is not particularly effective by any stretch,” he said. “It’s window dressing.”

That’s not to say Mina is opposed to testing — far from it. He just wants it to happen as close as possible to the flight itself: “20 minutes before you fly, or at the gate,” he said. And doing so would only be possible with rapid Covid-19 testing.

For months, Mina has been a vocal advocate for federal investment in rapid Covid-19 tests. These tests act as “contagiousness indicators,” allowing people to test frequently and know, virtually immediately, whether they should isolate themselves, he said in December. He argues that they are a better way of detecting people who can spread the virus than the gold-standard PCR tests, which are highly accurate but can take up to five days to return results. People can be highly contagious during the five days they are waiting for results and may unwittingly transmit the virus to people around them.

The Biden administration has announced that it will invest $50 billion in testing. Mina told reporters that he and his colleagues have been asking for $20 billion of that budget to go toward rapid testing. These tests are inexpensive, he points out, and with such a budget, it would be possible to push billions of these tests into the United States every month. Widespread availability of these tests would make it possible to create effective policies for fully reopening air travel as well as all other public services and events, like sports games, schools, and other forms of transportation.

On a different press call, Lenny Marcus, PhD, founding co-director of the National Preparedness Leadership Initiative, a program jointly run by the Harvard T.H. Chan School of Public Health, also voiced support for rapid testing for air travel.

“Eventually, yes, there has to be more widespread testing,” he told the Coronavirus Blog. “And something that we could be doing from our home very easily would be a big plus.”

For now, though, widespread availability of these tests remains an “aspiration,” as Marcus put it. Until then, people hoping to travel should strongly consider the point Mina has made: Getting a negative test three days before flying isn’t a guarantee that you won’t be contagious on a flight.

Restrictions on air travel have been tough on everyone, and they’ve prevented many people from seeing their loved ones, or even taking much-needed vacations, for many months. Mina’s guidance may be a hard reality to swallow for some people, and that’s understandable, but it’s important to keep it in mind as we work together to contain Covid-19’s spread.



Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Yasmin Tayag

Yasmin Tayag


Editor, Medium Coronavirus Blog. Senior editor at Future Human by OneZero. Previously: science at Inverse, genetics at NYU.